The EMBL-Hamburg Automated Crystal Structure Determination Platform is a system that combines a number of existing macromolecular crystallographic computer programs and several decision-makers into a software pipeline for automated and efficient crystal structure determination. The pipeline can be invoked as soon as X-ray data from derivatized protein crystals have been collected and processed. It is controlled by a web-based graphical user interface for data and parameter input, and for monitoring the progress of structure determination. A large number of possible structure-solution paths are encoded in the system and the optimal path is selected by the decision-makers as the structure solution evolves. The processes have been optimized for speed so that the pipeline can be used effectively for validating the X-ray experiment at a synchrotron beamline.

MX1 is a bending-magnet crystallography beamline at the 3 GeV Australian Synchrotron. The beamline delivers hard X-rays in the energy range from 8 to 18 keV to a focal spot at the sample position of 120 mm FWHM. The beamline endstation and ancillary equipment facilitate local and remote access for both chemical and biological macromolecular crystallography. Here, the design of the beamline and endstation are discussed. The beamline has enjoyed a full user program for the last seven years and scientific highlights from the user program are also presented.

A microfocus macromolecular crystallography beamline at the Australian Synchrotron is presented.

The ABC toxin complexes (Tc) produced by certain bacteria are of interest due to their potent insecticidal activity 1,2 and potential role in human disease 3 . These complexes comprise at least three proteins (A, B and C), which must assemble to be fully toxic 4 . The carboxy-terminal region of C is the main cytotoxic component 5 , and is poorly conserved between different Tcs. A general model of action has been proposed, in which the Tc binds to the cell surface via the A protein, is endocytosed, and subsequently forms a pH-triggered channel, allowing the translocation of C into the cytoplasm, where it can cause cytoskeletal disruption in both insect and mammalian cells 5 . Tc complexes have been visualised using single particle electron microscopy 6,7 , but no high-resolution structures of the components are available, and the role of the B protein in the mechanism of toxicity remains unknown. Here we report the three-dimensional structure of the complex formed between the B and C proteins, determined to 2.5 Å by X-ray crystallography. These proteins assemble to form an unprecedented, large hollow structure that encapsulates and sequesters the cytotoxic, carboxy-terminal region of the C protein like the shell of an egg. The shell is decorated on one end with a -propeller domain, which mediates attachment of the B/C heterodimer to the A protein in the native complex. The structure reveals how C auto-proteolyses when folded in complex with B. The C protein is the first example of a structure that contains RHS (rearrangement hot spot) repeats 8 , and illustrates a striking structural architecture that is likely conserved across both this widely distributed bacterial protein family and the related eukaryotic YD-repeatcontaining protein family, which includes the teneurins 9 . The structure provides the first clues about the function of these protein repeat families, and suggests a generic mechanism for protein encapsulation and delivery.ABC toxins were first identified, and have been best characterised, in the bacterium Photorhabdus luminescens 1 . However, the entomopathogenic bacterium Yersinia entomophaga contains a related Tc locus that includes an A component encoded by two ORFs (yenA1 and yenA2), a single B gene (yenB) and two C genes (yenC1 and yenC2), 10 the products of which associate independently with the A and B proteins, giving rise to two Tcs from one genetic locus. The C proteins of this and other Tcs are similar to the "polymorphic toxins" described by Zhang et al. 11 as they have a conserved RHS-repeat-containing amino-terminal region and a variable carboxyterminal region 10 . The carboxy-terminal regions (CTRs) of the Y. entomophaga C proteins are predicted to have different toxic activities: the C1 CTR is homologous to cytotoxic necrotising factor 1 (CNF1) from Escherichia coli 12 , whereas the C2 CTR is homologous to the deaminase YwqJ from Bacillus subtilis 13 . As in related complexes 3 , when the B subunit is co-expressed with either of the C subunits, C is cleaved at the boundary between th...